Scripted expressions editor gives unexpected results
I answered my self when I posted this question :D
The scripted expression is working in radians by default and is auto converted to degrees in the spotlight object. So what I did was: var - 5 and got my range just in the sweetspot.
Now it goes approximately from 1 to 172 deg.
I'm not sure for the precise math behind it, but it is working for me. If you need in depth how the math is functioning, check degrees to radians conversion.
Cheers!